Move Bullet 2.x demos in a single demo 'AllBullet2Demos', for now only BasicDemo and FeatherstoneDemo is implemented.

btgui/OpenGLWindow/GLInstancingRenderer.h

@@ -66,6 +66,7 @@ public:
 
 	void InitShaders();
 	void CleanupShaders();
+	void removeAllInstances();
 
 	void updateShape(int shapeIndex, const float* vertices);